Every ultrasonic cleaner gets a score from 0 to 100% built from five factors, which maps onto the 5-point rating shown on the site (a 0% score would be 1.5 stars; a perfect score, 5). Each factor is scored against fixed reference points, not against the other products in the list, so adding a new model never moves another model’s rating. Cleaners are grouped by tank volume, under 3 L, 3 to 10 L and 10 L and up, and use the same scale in every group.
| Factor | Measures | Weight |
|---|---|---|
| Value | price per liter of tank | 30% |
| Ultrasonic power | ultrasonic watts per liter of tank | 25% |
| Heater | heater watts per liter of tank | 10% |
| Features | degas, dual or sweep frequency, power control, drain, basket and a long timer | 25% |
| Warranty | warranty length | 10% |
Where the numbers come from
Tank volume, tank size, ultrasonic and heater power, frequency, timer, modes and warranty come from the maker’s specification sheet or brochure where one is published, and otherwise from the maker’s own copy on a retail listing. Where a maker’s figures conflict (for example a title that gives one frequency and a bullet that gives another), the figure is left out rather than guessed. Prices are checked at the stores each page links to, and the lowest is used.
The factors
Value is the current price divided by the tank volume, in dollars per liter, on a log scale, so halving the price always counts the same. $250 per liter scores zero and $8 per liter full marks. Small tanks cost more per liter than large ones, which is one reason products are ranked within their size group.
Ultrasonic power is the maker’s stated ultrasonic output divided by the tank volume, in watts per liter: 10 W per liter scores zero and 50 W per liter full marks. Only a figure the maker labels as ultrasonic power counts. Heater watts, total input power and peak power are never used; where a maker gives both effective and peak power, the effective figure is used. A listing that gives a transducer count without a wattage, or a single wattage without saying whether it is ultrasonic output or total input, has no ultrasonic power recorded.
Heater is the heater power divided by the tank volume, in watts per liter: 10 W per liter scores zero and 50 W per liter full marks. A stronger heater brings a full tank up to cleaning temperature sooner.
Features is 20% for a degas mode, 20% for dual frequency or a sweep mode, 15% for a gentle, low or adjustable power setting, 15% for a drain valve, 15% for an included basket and 15% for a timer that runs 60 minutes or more.
Warranty is the maker’s warranty: 1 year scores zero and 3 years full marks.
What isn’t scored
Tank dimensions, temperature range, frequency itself (beyond dual or sweep), control type, tank steel grade, weight and release date are listed but not scored.
Missing data
Ultrasonic power per liter is what separates these cleaners most, so a cleaner whose maker doesn’t publish its ultrasonic power gets no credit for it: that factor scores zero and the product page marks it as estimated. Warranty works the same way: a maker that doesn’t publish one gets no warranty counted, so that factor scores zero, the same as a one-year warranty, and is marked estimated. If the heater power or price isn’t published, that factor gets the neutral middle score (50) and is marked estimated. A feature the maker doesn’t mention counts as absent.
Ties and discontinued models
Products are ranked by score within each group. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.